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Industry Solutions for Drive Technology

Pump Application

Field of Applications

NMTG Non-Reverse Ratchets (Holdback/NRR) Solution for Pump Application

Holdback clutch is also known as a synonym below

  • Freewheel One Way Clutch
  • Non Reverse ratchet (NRR)
  • Uni-Directional Clutch
  • Anti-Runback device
  • Anti-Rotation Device
  • Backstop Device

Application 1

  • Application: Vertical Motors – Vertical Pumps
  • Product Name: Holdback /Backstop Device
  • Model Name: NHB (Centrifugal Lift-off Sprag type)
  • Freewheel one way clutch is used as: Backstop/Holdback
  • Mounting Location: Non-Drive end of the motor/Pump shaft
  • Function: To Prevent Reverse Rotation of Motor Shaft from Reverse flow of Water at shutdown or Switch off.

Purpose of Use and Operation Overview

For vertical pumps or vertical motors, there are some cases where reversing operation is restricted depending on the specification or use purpose. The figure above shows an example of equipment attached with a check valve. Normally, water flows in the direction of . The check valve is used to prevent the reverse flow ( ) of the water. If this check valve is damaged, the water may flow in the reverse direction and a pump may be operated reversely at high speed. Such reverse operation may cause system damage due to reduced lubrication of metal bearings. An effective counter measure is to attach a clutch to position 1 or 2 in the figure above as a backstop.

Apllication Images

Application 2

  • Application: Vertical Motor – Vertical Pump
  • Product Name: Non-Reverse Ratchet (Ratchet-Pin type)
  • Model Name: NRVC
  • Freewheel one way clutch is used as: Backstop/Holdback
  • Mounting Location: Non-Drive or Drive end of the motor shaft
  • Function: To Prevent Reverse Rotation of Motor Shaft from Reverse flow of Water at shutdown or Switch off.

Introduction NMTG Non-Reverse Ratchet (Ratchet-Pin type):

  • Non-Reverse Ratchets (Holdbacks) are typically used in Deep well Vertical Turbine Pump applications where Electric motors drive Pumps. For example, Deep well pumps are used for irrigation water as well as for drinking water supply.
  • A Non-Reverse Ratchet, here in also referred to as NRR, provides immediate protection against reversing due to phase reversals or from backspin (Reverse flow of Water at shutdown). The NRR prevent reverse rotation of shaft of the vertical motor while the pump water column is receding. As the water flows back into the well, it will run the pump and electric motor in reverse at unbounded speed that could reach destructive levels for either Pump or Motor or Both.

Working Principle

  • In NRR, Bottom Hub is fixed with structure & Top Hub is connected to Shaft through key. Now When Motor starts, Ratchet pin (located through Bottom Hub & Top Hub) will rotate & when Lift-off speed is achieved, Ratchet pin will Lift-off completely from Bottom Hub (because of Centrifugal Force). So, NRR will be in Freewheeling condition.
  • When Motor Power is switched off, Speed will decrease gradually & Ratchet pin will recess on Bottom hub. Now when Pump shaft will try to rotate in reverse direction, Ratchet Pin will completely locked to Bottom Hub & Prevent Reverse Rotation

Features

  • Suitable for Vertical Motor Shaft Application
  • Lubrication as well as Maintenance free
  • Wide Permissible limit for Radial & Axial Alignment
  • Noiseless in Running Condition
  • Complete wear free in Running condition hence Long life

Application 3

  • Application: Boiler feed pump, Water demineralization plant, Energy Recovery System
  • Product Name: Freewheel One-way Clutch / Housing Freewheel Clutch / Overrunning Clutch
  • Model Name: NHFC
  • Freewheel one way clutch is used as: Overrunning Clutch
  • Function: An application to alternately repeat the conditions where the inner and outer races of the clutch engage to transmit the torque and where they continue spinning around depending on the difference in the rotation speed or rotation direction.

Features: NHFC
(Housing Freewheel Clutch - Foot Mounted Type)

  • NHFC model is Housing type Freewheel one way clutch box.
  • At high speeds, which are the same or similar in freewheeling operation in driving operation.
  • This model applicable where assembly can be driven from two or more driving & driven members at same or similar high speed.
  • This Housing type NHFC freewheels are completely enclosed freewheels for stationary arrangement with input & output shaft.

The Housing freewheels must be mounted on input shaft diameter and output shaft diameter. Housing flywheels connection made by Coupling connected on Housing Flywheel shafts into complete assembly arrangement

Purpose of Use and Operation Overview

At the beginning of equipment startup, The motor drives the pump and water is sent to the required sections. The water circulates through the various sections and then returns to the pool under high pressure. This high pressure of the water before it returns to the pool is used to drive the recovery pump. The Housing Freewheel Clutch overruns while the pump is driven by the motor. When the recovery pump starts up and its speed reaches the motor speed, the cam clutch box automatically engages to reduce the load on the motor. This saves on power consumption by the motor, resulting in energy savings and CO2 emission reduction.

Advantage of using the Housing Freewheel Clutch

  • The Housing Freewheel Clutch engages automatically without the need for an extra control device.
  • Since the loss in the power transmission can be reduced, you can expect an effect even in a facility with low capacity.

Application Images